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Help!!!!! Extreme over voltage from ohio generator alternator!

9K views 32 replies 10 participants last post by  peva 
#1 ·
I have a 2000 Dodge Intrepid with the 2.7L engine with about 127,000 on her. I've had an ohio generator alternator on her for about two and half years that I bought second hand from a friend who had it for about 3 years before me. So when the bearings went out on me i wasn't two surprised. I sent it in to ohio gen and after alot of hassle I got it back in about a week and a half. It came with a spec sheet that had it putting out about 211 amps at like 6000rpm. pretty impressive for a 100 dollars in parts plus shipping and handling.

Now the bad.... I can't go above about 3 and a half grand and the alternator surges my voltage to 18volts or more. Its hard to tell since my volt gauge isn't the highest quality but anyways back on topic the voltage stays there and won't go down unless i unplug the two pin connector on the alternator and drive around without an alternator for about 10 or 15 mins. My car lights up like a chrismas tree including all headlights, dash lights, and interior lights and then the headlights, the dash lights and shift indicator shut off and wont go back on till i unplug the alternator. but the interior lights stay on no matter what i do untill i unplug the alternator and run the car until voltage drops below about 12volts

Im freaking out about this but all cell phones, and landlines around me dont work since some idiot cut a fiber optic cable near my town earlier today and I cant call ohio gen to see if they have any idea what it might be. please help me out guys.. you think it would be the voltage regulator or one of those two wires going to the plug on the alt. any suggestion is welcome im desperate
 
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#5 ·
I'm pretty sure that entails replacing the whole pcm. and I would like to avoid that at all costs.
Plus I don't believe that would be solving the cause of the problem being that I have had this alt. in my car for little over a two years and haven't had any electrical problems with this until ohio gen rebuilt it and sent it back to me.

I never had the alt. tested when i bought it second hand so I'm not sure what it was putting out for amps but it did fix my dimming lights problem so it had to be putting out more amps than my original alt. that had around 100,000 miles on it.

would the simple fact that it's rebuilt and putting out even more amps than before somehow overloaded the voltage regulator?
Why would the alt. kick on and stay on when the engine goes above 3500 rpms putting 18volts constant to the car and continue to do that no matter if I turn the car off and back on or if i disconnect the plug on the alt for a short while and plug it back in before i drive with it disconnected for a while?

after it's disconnected and I let the car sit for awhile and then plug it back in the voltage regulator seems to be in perfect working order because it keeps the voltage at right around 14volts just like it always used to be?

Any thoughts anyone? Sorry I have so many questions but I love this car to death and I'm not giving up on it just yet.
She's still got about 350,000 miles left before I let her rest in peace. :D
 
#7 ·
I'm sorry to say I already checked them :glum: They weren't corroded just a tad bit salty from Wisconsin winters but just in case I did clean them again.

Thanx for the input though

:whistle: I have been known to over think things before lol quite a few that I'd like to forget still haha

Any other thoughts?
 
#6 ·
something is goofy here,, if all was ok with the old alt, and this is going on with the new,,, first thought is the alt itself,,, second thought is like said above, bad connection,, ground etc. thought 3, is bad pcm,, as the pcm controls the voltage,,,,there is no regulator
 
#8 ·
^This.

I would start with a proper factory alternator, and check all connections and cables, for corrosion, looseness, etc.

Ive had bad luck in the past with "rebuilt" alternators from some random shop. Not recommended.

Alternators are quite an uncommon failure on these cars, so you could get away with a used one from the boneyard, provided it doesnt have a million miles on it.

That would be a good start, and cheaper than a PCM.
 
#10 ·
I don't know squat about Ohio Generator's products but, is this wired differently than a conventional alternator? The PCM controls the stock units as the regulator is built into the PCM. Does this unit you have use an external regulator?
 
#16 ·
Double check that your voltage gauge is reading correctly. Perhaps it is failing. Plus, it's a simple check.
 
#18 ·
Well to update you guys on this problem its all fixed and as far as i can tell no permanent damage was caused i hope.... Unfortunately it was caused by my own stupidity and I apologize to everyone that suggested checking my ground haha.. My zero gauge wire running from my battery to the car slipped out of its crimped connector and I didn't realize it because I had taped it to prevent as much corrosion as I could from these lovely salty winters in Wisconsin. After triple checking all my connections again and fixing the bad ground wire everything worked perfect.... Thanx again guys just promise not to rip on me to bad for this one haha
 
#23 ·
Sorry to say guys but it's not a happy ending just yet.... yesterday the problem came back on the way to work. except that its over charging at idle now too.. I work at a remote start/ audio shop so I bought all new 0 gauge wire and redid every single connection between the engine, the alternator, the battery, and the body of the car. The overvoltage seemed to be fixed for about ten min and then it happened again just while the car was idling.. Im so stressed from this I dont know what to do.

Has this ever happened to anyone else? I don't want to be constantly worrying that my car is going to fry itself. And I really dont want to take it to the dealer.
 
#24 ·
Maybe time for a replacement standard alternator? New, used or rebuilt. I'd buy a used alternator from a wrecking yard. They're not that expensive.
 
#26 ·
I went through the fsm and found the trouble shooting guide for code p0622 at least i think thats the number haha I just know the code was something along the lines of generator field fault.

everything checked out alright with the help of a snap on scanner thats able to actuate the gen field on demand.
So I called ohio gen and talked to tom, the guy who actually rebuilt it and when we got to talking about the gen field connector and how the wires are controlling the alt. He said that one of the wires is supposed to be grounded and the pcm controls the field by varrying positive voltage on the other wire... I'm not sure if i remember correctly but when looking at our wiring diagrams it looked like our cars apply 12V on one wire and control the field by varying the ground on the other wire. Is that correct? When I mentioned that to him he assured me that either way works and doesn't matter either way. I have a pretty good understanding of electric circuits but my knowledge falls short in this department so if anyone has some knowledge please share ha
 
#27 · (Edited)
Pre-'02, there is a constant +12 volts on one side of the field winding, and the PCM diddles the ground on the other side. Starting in '02, the end of the field winding is grounded, and the PCM controls charging by varying the current from the positive side.

I'm not 100% sure, but I believe the current has to be in the correct direction. Since he apparently assumed the opposite of what your car really is, I have to wonder if yours would work correcly if you swapped the field winding connections to put the control current in the opposite direction. However, it could very well be that the polarity doesn't matter since the diodes in the alternator automatically rectify its output.

Like you, I know electronics too, but not enough about this to be sure either way. If it was me, I'd reverse the field winding connections and see if that fixes it - but don't be surprised if nothing changes.

EDIT: The more I think about it, the more I *think* the field polarity wouldn't matter (but, again, not 100% sure).
 
#28 ·
Pre-'02, there is a constant +12 volts on one side of the field winding, and the PCM diddles the ground on the other side. Starting in '02, the end of the field winding is grounded, and the PCM controls charging by varying the current from the positive side.

I'm not 100% sure, but I believe the current has to be in the correct direction. Since he apparently assumed the opposite of what your car really is, I have to wonder if yours would work correcly if you swapped the field winding connections to put the control current in the opposite direction. However, it could very well be that the polarity doesn't matter since the diodes in the alternator automatically rectify its output.

Like you, I know electronics too, but not enough about this to be sure either way. If it was me, I'd reverse the field winding connections and see if that fixes it - but don't be surprised if nothing changes.
Do you mean just flip flop the wires in the field connector? It would be worth a shot but it still wouldn't be grounding one wire and "diddling" with the positive side. (Your use of diddling just made my day haha)

Plus it still doesn't explain how everything was fine for about two days and then it started acting up again.

Also its interesting that you brought the point about how pre '02 and post '02 are different on how they regulate the alt. because, I actually bought the alternator from an installer from a local rival audio/remote start shop. His intrepid was an 04 and I'm sure he told ohio gen that when he bought the alt. so i'm wondering if they change something inside the alt. when they build it... but anyways my point is that I ran this alt in my car for close to two years with no problems... until the bearing went out that is. Now after i sent it back to them and said it was for a 2000 trep I start having problems.... As an afterthought that sounds more like a conspiracy haha I guess its food for thought.

The plus side of this lovely story is since my buddy was junking his intrepid because it had over 250000 on it and the water pump was starting to fail for the third time lol ..... I got to strip his car of all the goodies like pleather door panels and swap them for my ugly faded diamond pattern carpet ones haha Sorry to rant on but thinking on the plus side is nice considering I've been puddle jumping from place to place on nothing but a battery so i try to conserve it by running no radio, head lights only when i absolutely need them, and most importantly no heater which sucks being it was around 41 degrees where i live today

Thanx again for your brainstorming i can't wait to actually be able to drive my baby and not just limp her around
 
#31 · (Edited)
I believe the connectors are different between 1998-2001 and 2002-2004 cars.


Edit: Yes they are different in shape if you have a 3.2/3.5L. The 2.7 appears to be the same 1998-2004. You have a 2.7L I believe so any 1998-2004 alternator should work for you. Too bad it's such a PITA to change on a 2.7L unlike the 3.2/3.5.


1998-2001:


2002-2004:
 
#33 ·
...Too bad it's such a PITA to change on a 2.7L unlike the 3.2/3.5....
...The only thing I haven't swapped out is the pcm. I'm gonna have to bite the bullet and go grab an alt from the junkyard on monday and put that one in...
Yeah - I replaced my 2.7 alternator a couple of years ago. I hope to never have to do that again!
 
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